Automatic apparatus for controlling the childbirth labor

ABSTRACT

Apparatus for controlling the childbirth labor comprising an electromyographic unit ( 4 ) with sensors ( 3 ) for detecting electrical signals of a parturient&#39;s uterus and means ( 6 ) for analyzing and processing the electrical signals, and a pneumatic belt ( 1 ) to be fixed around the parturient&#39;s abdomen having sensors ( 15 ) to detect the variation of the internal pressure due to uterine contractions, and means ( 2 ) for inflating the belt to provide a thrust as an aid for the expulsion of the fetus, where a device ( 7 ) is provided, associated with sensors ( 15 ) and ( 3 ) to control the activation of means ( 2 ) for the inflation of the pneumatic belt ( 1 ).

FIELD OF THE INVENTION

The present invention refers to an automatic apparatus for controllingthe childbirth labor.

BACKGROUND OF THE INVENTION

It is known that the term “childbirth labor” refers to the complex ofmechanical and dynamic phenomena which lead to the expulsion of thefetus and placenta and which, conventionally, is subdivided into threestages. The first stage, which relates to the dilatant period, that is,to the beginning of the labor up to the complete dilatation of theuterine cervix, is in turn subdivided into a “latent period”,characterized by a dilatation of 3–4 cm, and a following “active period”which leads to a complete 15 dilatation. The second stage, which relatesto the expulsive period, goes from the complete dilatation to thedelivery. The third stage, which relates to the discharge of theafter-birth, ends up with the expulsion of the placenta.

It is also known that the deficiency, alteration or insufficientcoordination of the uterine contractions may cause problems upon theexpulsive stage, which is the delivery's most delicate one. Inparticular, it may happen that the uterus is not able to produce, withits contractions, a force of an intensity sufficient to conclude thedelivery's expulsive stage (hypokinesia). It may happen, besides, thatthe expectant mother, in spite of the therapies commonly provided fortreating such cases, is unable to produce a thrust—through acorresponding contraction of the abdominal press—adding up to the forcegenerated by the uterine contraction. And, since a prolonged rest of thefetus in the delivery duct may seriously endanger the health conditionthereof, a so-called Kristeller maneuver is generally performed by thehealth personnel, which consists in exerting, with an arm, a series ofthrusts upon the bottom of the uterus, with the purpose of assisting thenatural expulsive forces and speeding up the progression anddisengagement of the fetus. However, this maneuver has risks inasmuch asit may cause the rupture of the uterus, the detachment of the placentaand acute fetal pains as well.

Also known in obstetrics is the use of the electromyograph (EMG) bywhich it is possible to register the electrical phenomena of the uterus'natural and involuntary contractions by deriving the relevant electricalpotentials via electrodes applied on the patient's abdomen: anapplication software to be run on a PC provides for a graph of saidelectrical potentials versus time. However, the use of only an EMG doesnot provide any aid to the parturient's thrust and, moreover, thecontraction graphs plot also other spurious signals such as spikes,tensions induced by the activation of other apparatuses and by neon glowlamps.

Also known in obstetrics is the use of the Pressure Labor Assister(PLA), with pressure sensors-controlled software, which utilizes thepressure increase inside an air chamber—formed within an abdominal bandfixed around the patient's body—and which occurs as a consequence of thenatural uterine contractions, to provide an automatic extra force, as anaid to the parturient, for the expulsion of the future baby.

On the other hand, this known device PLA does not provide a chart nor arecord of the uterine contractions, and may also be a source of dangers,inasmuch as the possible overpressures on the pneumatic band, which areindependent of the contractions but are due instead, for example, tomore or less involuntary movements of the parturient, are alwaysinterpreted as a signal of uterine contraction and, in such case, it mayoccur that the consequent inflation of the abdominal pneumatic band willtake place during a rest period, between one contraction and another,thereby dangerously reducing the inflow of blood to both the parturientand future baby.

SUMMARY OF THE INVENTION

One object of the present invention is to overcome the drawbacks of thecommon and widespread Kristeller technique.

A further object of the present invention is to enable, in case ofascertained insufficient expulsive force of the uterine naturalcontractions, the person in charge of the childbirth to activate adevice providing an extra thrust for the expulsion of the fetus—theactivation of said device depending, for a higher safety measure, on theuterine contraction and not on false signals.

The advantages deriving from the present invention lie essentially inthe fact that it is possible to automatically ensure, whenever the needarises and in a non-invasive fashion, the highest accurate coordinationbetween the internal thrust produced by both natural and involuntaryuterine contractions and the supplementary thrust produced by means of apneumatic belt intended to act on the parturient's abdomen; that anapparatus according to the invention is safe, utilizable with relativesimplicity by the personnel assisting the expectant mothers, relativelysimple to make and reliable also after a prolonged service period. Allthis by making use of an integrated system allowing the auxiliarypneumatic thrust to be obtained only when the parturient hascontractions detected simultaneously and safely by both pneumatic andelectrical signals independent from each other and deriving from saidcontractions.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a simplified block diagram of an apparatus according to theinvention, showing a possible configuration thereof upon use;

FIG. 2 is a schematic plan view of the pneumatic belt (1) shown in theschematic diagram of FIG. 1; and

FIG. 3 is a further simplified block diagram of an apparatus accordingto the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, FIG. 1 shows a means fordetecting the electrical activity of the uterus, comprising two or moreouter electromyographic sensors (3) (that is, sensors of non-invasivetype) able to be positioned on the skin of the parturient's abdomen attwo regions corresponding to preset points of the uterus U. Alsoprovided are a means for registering and plotting the electrical signalsof the uterine contractions thus detected and a means, which includes anelectromyographic apparatus (4) and an interface (5), for analyzingelectrical signals in relation to a predetermined scheme of analysis. Aninflatable belt (1) is provided that is associated with pneumatic means(2) able to inflate it under control and at preset pressure, andrespectively deflate it. The belt (1) is put on by the expectant motherin such a way that a surface (10) of the same belt will act, wheninflated, upon the bottom of the uterus. A means (7) is provided tocontrol the activation and deactivation of said pneumatic means (2) inresponse to the pressure variation due to the contraction and sensed bythe pneumatic belt, and to the result of analysis of the uterus'electrical activity.

In particular, the analysis means comprise an electromyographicapparatus (4), associated with said sensors (3) via an interface (5)allowing the amplification and preprocessing of the signals and providedwith a section (6) for processing the signals detected by the sensors(3) and transmitted through the interface (5) with their respective timevalue, as best described later on in greater detail.

In case of two-channel electromyographic apparatuses, such as the TECASinergy Multimedia of the Oxford Instruments, two channel sensors orelectrodes and one ground electrode are used: the channel sensors arepositioned symmetrically and horizontally in a skin region of theparturient's abdomen at about 5–15 cm of the umbilical transverse, andthe ground electrode is located on the internal side of the left thigh.As for the inflatable belt (1), this is of a type comprising an airchamber (11) with a coupling (12) for a tube (13) connectable to saidmeans (2), and provided with two wings (1 a) of a length sufficient forbeing tied up around the parturient's thorax: the wings (14) being ableto be linked one to the other by Velcro-type means 140 after the belthas put on. Moreover, the pneumatic means (2) is internally providedwith sensors (15) able to detect the pressure variations inside the airchamber (11), which are due to the thrusts exerted by the parturient'sabdomen as a consequence of the uterine contractions, that is, relativeto a basic pressure value corresponding to the initial inflation (forexample, when using a belt of MITECH-200-A type, a basic value of 8–16kPa). The belt in question is intended to exert, as best described lateron, a predetermined pressure P uniformly distributed on the uterus'bottom.

Provided upstream of said pneumatic means (2) is an activation device(7) which, in turn, is associated with sensors (15) located within themeans (2), and with the electromyographic apparatus (4): the device (7)determining the activation of the pneumatic means (2), that is, theinflation of the belt (1), whenever both the uterine contraction signalson output from the sensors (15) and the signals on output from theapparatus (4) are present therein at the same time.

To be more precise, if, during the labor, the device (7) receivessimultaneously both the electrical signals from the means (4)—resultingof such intensity and shape as to correspond to those of the uterinecontractions (for example, electrical signals three times higher thanthe signals sensed between one contraction and another)—and thepneumatic signals detected by the sensors (15) and identified ascontraction signals as well, then, only in this case the device (7)gives the command for the activation of the means (2), that is, for theinflation of the belt (1) at a pressure to be either preset or timelyestablished by the person in charge of the childbirth.

In other words, the activation of belt (1) and, accordingly, theauxiliary thrust P exerted by the latter on the parturient's abdomen incorrespondence of the uterus' bottom, takes place solely when there isoccurring, simultaneously, on the one hand, an overpressure in hechamber (11) of belt (1) due to a deformation imposed by the abdominalmuscles on the belt's wall because of a contraction and, on the otherhand, that is, in correspondence of sensors (3), a myoelectricalactivity of preset intensity and in any case exceeding the intensitybeing present when no contractions occur. The two detections areindependent from each other, as being obtained from independentdetection means, but are both related to a same event, that is, to thenatural and involuntary uterine contraction upon the active stage of thechildbirth. It thus follows that the actuation of the belt (1) resultsprecisely in phase with the uterine contractions of greater intensity,as it is operated on the basis of detections made both within thechamber (11) of belt (1) and on the basis of detections made on themuscular electrical activity in the more directly involved abdominalregion.

The time for the activation of belt (I), that is, the time ofoverpressure persistence within the chamber (11) of the same belt undercontrol of means (2), is adjustable by the health operator who assiststhe expectant mother and whose decisions are taken according to thetrend of the electromyographic contraction signals previously registeredfor the same patient.

As above described, the device (7) which controls the activation of themeans (2) provided for the inflation of the belt (1) is commonlyassociated with the pressure sensors (15) and with the electricalsensors (3) as well. However, the operator may cut off one or the otherconnection, owing to a malfunction of one of them or when he/she deemssuited to do so. For example, it is possible to exclude the connectionwith the pressure sensors (15) so that the activation of the pneumaticmeans (2) is controlled solely by electrical signals transmitted by thesensors (3); otherwise, it is possible to cut off the sensors (3), sothat the activation of the pneumatic means (2) is controlled solely bypressure signals transmitted by the sensors (15). All this makes itpossible to use the device in question also in case of malfunctionsaffecting either the detection of pressure signals through the sensors(15) or the detection of signals transmitted by the sensors (3), and toprocess the signals by 10 means of the electromyographic apparatus (4,6). In any case, the operator has faculty of excluding the automaticintervention of the system in order to use the latter only when the needarises.

With reference to the diagram of FIG. 3, the device (7) comprises an ANDgate (70) whose inputs are connected, respectively, to the output of theapparatus (4) and to the output of an A/D converter (150) provideddownstream of sensors (15) housed in the belt (1). The output of saidAND gate is connected with the input of a D/A converter (72) which, onoutput, is connected with the means (2) which activate the inflation ofthe belt (1). Inserted on the line connecting the gate (70) with theconverter (72) is a normally closed switch (71). Inserted on the lineconnecting the converter (150) with the converter (72) is a normallyopened switch (73). When the sensors (15) sense an overpressure in thechamber of belt (1), a corresponding electrical signal is producedwhich, after being converted in digital form by the converter (150), isfed to the AND gate (70). Similarly, the signals on output from thesection (6) of the electromyographic apparatus (4) come to the AND gate(70) which, when both signals are present, activates, through theconverter (72), the opening of a solenoid of means (2) and, therefore,the inflation of the belt (1). The operator may decide to cut off theAND gate (70), for example in case of ascertained failure of theapparatus (4), by merely opening the switch (71) and closing the switch(73). The switches (71) and (73) operate in push-pull mode.

The data processing section (6) can advantageously consist of a PCassociated with the electromyographic unit (4). Within the section (6),the signals coming from the sensors (3) and acquired by the system areprocessed according to a preset algorithm, for example, the onedescribed in the article “A fast algorithm for detecting contractions inuterine electromyography—a non invasive method utilizing higher-orderzero crossing for signal analysis” published in IEE Engineering andBiology—March/April 2000. Such an algorithm allows the obtainment of anestimator value to be compared with a predefined threshold. Throughoutthe time interval in which the estimator value exceeds said threshold,it is assumed that a contraction is taking place and a signal of logiclevel one is fed to the AND gate (70). Vice versa, when the estimatorvalue is below said threshold value, a signal of logic level zero is fedto the AND gate (70).

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

1. Apparatus for controlling childbirth labor comprising: anelectromyographic unit with sensors associated therewith for detectingthe electrical signals of a parturient's uterus and means for analyzingand processing said electrical signals; a pneumatic belt to be fixedaround the parturient's abdomen and having sensors associated therewithto detect the variations of internal pressure of an interior of saidpneumatic belt due to uterine contractions, and means for inflating saidbelt to provide a thrust as an aid for the expulsion of the fetus; and adevice associated with the electromyographic unit and the pneumatic beltsensors and to control the activation of said means for inflating thepneumatic belt.
 2. Apparatus according to claim 1, characterized in thatsaid device comprises an AND gate with AND gate inputs being connected,respectively, to an output of said electromyographic unit and to anoutput of an A/D converter located downstream of said sensors which areassociated with the belt, and with an AND gate output being connectedwith the input of a D/A converter, wherein the D/A converter output isconnected with said means for inflating the belt.
 3. Apparatus accordingto claim 2, characterized in that a first switch is inserted on a lineconnecting the AND gate with the D/A converter.
 4. Apparatus accordingto claim 3, characterized in that a second switch is inserted on a lineconnecting the A/D converter with the D/A converter, said second switchoperating in push-pull mode with respect to said first switch. 5.Apparatus according to claim 2, characterized in that a second switch isinserted on a line connecting the A/D converter with the D/A converter.6. Apparatus according to claim 1, characterized in that said means foranalyzing and processing of the electromyographic unit consist of a PCassociated with the electromyographic unit.
 7. Apparatus for controllingchildbirth labor, said apparatus comprising: an electromyographic unitwith sensors associated therewith for detecting electrical signals of aparturient's uterus; means for analyzing and processing said electricalsignals; and a pneumatic belt adapted to be fixed around a parturient'sabdomen having sensors associated therewith to detect the variations ofan internal pressure of an interior of said pneumatic belt due touterine contractions; and means for inflating said belt to provide athrusting force to aid in expulsion of a fetus, including a controlassociated with the electromyographic unit and the pneumatic beltsensors for controlling the activation of said means for inflating saidpneumatic belt.
 8. Apparatus according to claim 7, wherein said devicecomprises an AND gate with AND gate inputs being connected,respectively, to an output of said electromyographic unit and to anoutput of an A/D converter located downstream of said sensors which areassociated with the belt, and with an AND gate output being connectedwith the input of a D/A converter, wherein the D/A converter output isconnected with said means for inflating the belt.
 9. Apparatus accordingto claim 8, wherein a first switch is inserted on a line connecting saidAND gate with said D/A converter.
 10. Apparatus according to claim 9,wherein a second switch is inserted on a line connecting the A/Dconverter with the D/A converter, said second switch operating inpush-pull mode with respect to said first switch.
 11. Apparatusaccording to claim 8, wherein a second switch is inserted on a lineconnecting the A/D converter with the D/A converter.
 12. Apparatusaccording to claim 7, wherein said means for analyzing and processing ofthe electromyographic unit comprises a PC associated with theelectromyographic unit.
 13. Apparatus for controlling childbirth labor,said apparatus comprising: a pneumatic belt to be fixed around aparturient's abdomen; a means for inflating said pneumatic beltproviding a thrust as an aid for explusion of a fetus; electromyographicsensors; pressure sensors; a device for controlling activation ofinflation means of said pneumatic belt, wherein said device isresponsive to signals from electromyographic sensors and to pressuresensors that detect variations of internal pressure within saidpneumatic belt due to uterine contractions; and a means for analyzingand processing said signals.
 14. Apparatus according to claim 13,wherein said device comprises an AND gate with AND gate inputs beingconnected, respectively, to an output of said electromyographic sensorsand to an output of an A/D converter located downstream of said pressuresensors for detecting variations of internal pressure within the belt,and with an AND gate output being connected with the input of a D/Aconverter, wherein the D/A converter output is connected with said meansfor inflating the belt.
 15. Apparatus according to claim 14, wherein afirst switch is inserted on a line connecting said AND gate with saidD/A converter.
 16. Apparatus according to claim 15, wherein a secondswitch is inserted on a line connecting the A/D converter with the D/Aconverter, said second switch operating in push-pull mode with respectto said first switch.
 17. Apparatus according to claim 14, wherein asecond switch is inserted on a line connecting the A/D converter withthe D/A converter.
 18. Apparatus according to claim 13, wherein saidmeans for analyzing and processing said signals comprises a PCassociated with the electromyographic sensors.